LONDON (Reuters) – For the first time, doctors report on the replacement of a major blood vessel with an donor vein that was repopulated with the recipient’s stem cells.

The operation, to replace a 10-year-old girl’s portal vein, was reported online in The Lancet medical journal today.

It could open the door to stem cell-based grafts for heart bypass and dialysis patients who lack suitable blood vessels for replacement surgery, and the Swedish team said it is now working with an undisclosed company to commercialize the process.

“I’m very optimistic that in the near future we will be able to get both arteries and veins transplanted on a large scale,” said Dr. Suchitra Sumitran-Holgersson of the University of Gothenburg, a member of the team that performed the operation in March 2011.

Four years ago, a 30-year-old woman received the world’s first transplant of a trachea that was grown in a similar way, by seeding a stripped-down donor organ with her own stem cells. Other such trachea operations have followed since.

In the latest case, surgeons took a 9 cm (3.5 inch) section of iliac vein from a deceased donor and removed all the living cells, leaving just a protein scaffold tube. Stem cells extracted from the girl’s bone marrow were then injected onto the tube and two weeks later the graft was implanted.

The new blood vessel immediately restored normal blood flow, the doctors said, although after a year it narrowed and a second stem cell-based graft was needed.

Drs. Martin Birchall and George Hamilton of University College London said in a commentary in The Lancet that the Swedish doctors had spared the young girl the trauma of having veins harvested from deep in her neck or leg and avoided the need for a liver transplant.

But they cautioned the technique now needed to be tested in clinical trials and developed into a straightforward quality-controlled production process.

Dr. Sumitran-Holgersson said her team had already simplified the process and was now able to harvest stem cells from blood rather than bone marrow. She aims to test the technique with arteries later this year.

“You are going to see more and more of these personalized grafts in future,” she said in a telephone interview.

Around the world, scientists in the emerging field of regenerative medicine are working to engineer many different human organs and tissues in the lab, including lungs and hearts.

Building such complex organs is a lot more challenging than making blood vessels, however, since veins are relatively simple hollow structures with few engineering demands.